made some modifications to the Mermaid graph in python-book/src/*.md

[cosing]

I noticed an issue with the Mermaid diagram layout/rendering at ch01-introduction-and-motivation.html#rust-philosophy.

I've created a quick patch to fix it.

diff --git a/python-book/src/ch01-introduction-and-motivation.md b/python-book/src/ch01-introduction-and-motivation.md
index f586f48..b9ab24c 100644
--- a/python-book/src/ch01-introduction-and-motivation.md
+++ b/python-book/src/ch01-introduction-and-motivation.md
@@ -404,6 +404,7 @@ graph LR
         PY_GIL --> PY_OS["OS / Hardware"]
     end
 
+    PY ~~~ RS
     subgraph RS["🦀 Rust"]
         direction TB
         RS_CODE["Your Code"] --> RS_NONE["No runtime overhead"]
diff --git a/python-book/src/ch04-control-flow.md b/python-book/src/ch04-control-flow.md
index 3988bc0..0c88084 100644
--- a/python-book/src/ch04-control-flow.md
+++ b/python-book/src/ch04-control-flow.md
@@ -218,6 +218,8 @@ flowchart LR
         P2 --> P4["result used later"]
         P3 --> P4
     end
+
+    Python ~~~ Rust
     subgraph Rust ["Rust — Expressions"]
         R1["let result = if cond"] --> R2["{ 'yes' }"]
         R1 --> R3["{ 'no' }"]
diff --git a/python-book/src/ch05-data-structures-and-collections.md b/python-book/src/ch05-data-structures-and-collections.md
index 7242470..4efc124 100644
--- a/python-book/src/ch05-data-structures-and-collections.md
+++ b/python-book/src/ch05-data-structures-and-collections.md
@@ -195,6 +195,7 @@ flowchart LR
         PH --> PHT["height: float obj"]
         PH --> PD["__dict__"]
     end
+    Python ~~~ Rust
     subgraph Rust ["Rust Struct (Stack)"]
         RW["width: f64<br/>(8 bytes)"] --- RH["height: f64<br/>(8 bytes)"]
     end
diff --git a/python-book/src/ch10-traits-and-generics.md b/python-book/src/ch10-traits-and-generics.md
index eb449fb..56a7dfe 100644
--- a/python-book/src/ch10-traits-and-generics.md
+++ b/python-book/src/ch10-traits-and-generics.md
@@ -322,6 +322,7 @@ flowchart TB
         VT --> I1["Article::summarize()"]
         VT --> I2["Tweet::summarize()"]
     end
+    Static ~~~ Dynamic
     style Static fill:#d4edda
     style Dynamic fill:#fff3cd
 ```
diff --git a/python-book/src/ch11-from-and-into-traits.md b/python-book/src/ch11-from-and-into-traits.md
index 30e67e3..d5b2845 100644
--- a/python-book/src/ch11-from-and-into-traits.md
+++ b/python-book/src/ch11-from-and-into-traits.md
@@ -62,8 +62,9 @@ let n: i32 = "42".parse()?;                    // Propagate error with ?
 
 ### The From/Into Relationship
 
+<!-- Open to debate -->
 ```mermaid
-flowchart LR
+flowchart TB
     A["impl From&lt;A&gt; for B"] -->|"auto-generates"| B["impl Into&lt;B&gt; for A"]
     C["Celsius::from(Fahrenheit(212.0))"] ---|"same as"| D["Fahrenheit(212.0).into()"]
     style A fill:#d4edda
diff --git a/python-book/src/ch15-migration-patterns.md b/python-book/src/ch15-migration-patterns.md
index a39d528..49d96ef 100644
--- a/python-book/src/ch15-migration-patterns.md
+++ b/python-book/src/ch15-migration-patterns.md
@@ -250,8 +250,9 @@ let db_host = get_config()["database"]["host"].as_str().unwrap();
 
 ## Incremental Adoption Strategy
 
+<!-- Open to debate -->
 ```mermaid
-flowchart LR
+flowchart TB
     A["1️⃣ Profile Python<br/>(find hotspots)"] --> B["2️⃣ Write Rust Extension<br/>(PyO3 + maturin)"]
     B --> C["3️⃣ Replace Python Call<br/>(same API)"]
     C --> D["4️⃣ Expand Gradually<br/>(more functions)"]

Notes & Open Questions

• Open for discussion: note with <!-- Open to debate -->
• Since this is a very small change, feel free to cherry-pick/apply this patch directly, combine it into another PR, or let me know if you'd prefer me to open a standalone PR for it.

[adarshdhital007]

@cosing Could you please attach the images that demonstrate the issue? I’m not seeing any problems with the Mermaid chart on my end, so the screenshots would help me better understand and investigate the issue.

[cosing]

@adarshdhital007

On my screen, the first image in ch01-introduction-and-motivation.md looks like this,
I noticed that the intended approach was Graph LR, but because there were no connections, it actually turned into a top-down relationship

Similarly, for ch04 and ch05, after the fix, they become

If it doesn't appear on your computer, could it be related to the size of the webpage?

[cosing]

In fact, a similar issue was fixed in 05c7059 (or link it).

• python-book/src/ch01-introduction-and-motivation.md
• python-book/src/ch04-control-flow.md
• python-book/src/ch05-data-structures-and-collections.md
• python-book/src/ch10-traits-and-generics.md

Additionally, the changes to python-book/src/ch11-from-and-into-traits.md and python-book/src/ch15-migration-patterns.md are based on my personal preference, as I feel they make the code a bit clearer.

[adarshdhital007]

I am good with this PR being merged.

[cosing]

Regarding python-book/src/ch11-from-and-into-traits.md and python-book/src/ch15-migration-patterns.md — do you have any feedback on these?

There aren't any major issues, but they just don't seem clear enough to me.