various fix for 5gc api gen

Author: p1-alexandrevaney

openapi_python_client/utils.py

@@ -67,7 +67,7 @@ def to_valid_python_identifier(value: str) -> str:
     See:
         https://docs.python.org/3/reference/lexical_analysis.html#identifiers
     """
-    new_value = fix_reserved_words(fix_keywords(sanitize(value)))
+    new_value = fix_reserved_words(fix_keywords(sanitize(value))).lstrip('_')
 
     if new_value.isidentifier():
         return new_value