Change char to ch to resolve name conflict

integration_tests/test_str_01.py

@@ -81,4 +81,6 @@ def check():
     test_str_repeat()
     test_constant_str_subscript()
     test_str_title()
+    test_str_istitle()
+    test_str_isalpha()
 check()

src/runtime/lpython_builtin.py

@@ -766,12 +766,12 @@ def _lpython_str_upper(x: str) -> str:
 
 @overload
 def _lpython_str_isalpha(s: str) -> bool:
-    char: str
-    for char in s:
-        char_ord: i32 = ord(char)
-        if 65 <= char_ord and char_ord <= 90:
+    ch: str
+    for ch in s:
+        ch_ord: i32 = ord(ch)
+        if 65 <= ch_ord and ch_ord <= 90:
             continue
-        if 97 <= char_ord and char_ord <= 122:
+        if 97 <= ch_ord and ch_ord <= 122:
             continue
         return False
     return True
@@ -780,23 +780,23 @@ def _lpython_str_isalpha(s: str) -> bool:
 def _lpython_str_title(s: str) -> str:
     result: str = ""
     capitalize_next: bool = True
-    char: str
-    for char in s:
-        char_ord: i32 = ord(char)
-        if char_ord >= 97  and char_ord <= 122:
+    ch: str
+    for ch in s:
+        ch_ord: i32 = ord(ch)
+        if ch_ord >= 97  and ch_ord <= 122:
             if capitalize_next:
-                result += chr(ord(char) - ord('a') + ord('A'))
+                result += chr(ord(ch) - ord('a') + ord('A'))
                 capitalize_next = False
             else:
-                result += char
-        elif char_ord >= 65 and char_ord <= 90:
+                result += ch
+        elif ch_ord >= 65 and ch_ord <= 90:
             if capitalize_next:
-                result += char
+                result += ch
                 capitalize_next = False
             else:
-                result += chr(ord(char) + ord('a') - ord('A'))
+                result += chr(ord(ch) + ord('a') - ord('A'))
         else:
-            result += char
+            result += ch
             capitalize_next = True
 
     return result
@@ -809,17 +809,17 @@ def _lpython_str_istitle(s: str) -> bool:
         return False  # Empty string is not in title case
 
     word_start: bool = True  # Flag to track the start of a word
-    char: str
+    ch: str
 
-    for char in s:
-        if (char == ' ' or char == '\t' or char == '\n') and word_start:
+    for ch in s:
+        if (ch == ' ' or ch == '\t' or ch == '\n') and word_start:
             return False  # Found a space character at the start of a word
-        elif char.isalpha() and char.isupper():
+        elif ch.isalpha() and ch.isupper():
             if word_start:
                 word_start = False
             else:
                 return False  # Found an uppercase character in the middle of a word
-        elif char.isalpha() and char.islower():
+        elif ch.isalpha() and ch.islower():
             if word_start:
                 return False  # Found a lowercase character in the middle of a word
             word_start = False