Objective

Implement common_letters, a function that keeps shared characters without duplicates.

Steps

• Create common_letters.py.
• Expose def common_letters(left: str, right: str) -> str:.
• Scan left from start to end.
• Keep a character only if it also appears in right.
• Do not repeat a character that was already kept.
• The result order must follow the first appearance order in left.
• The comparison is case-sensitive.

Objective

Implement common_letters, a function that keeps shared characters without duplicates.

Steps

• Create common_letters.py.
• Expose def common_letters(left: str, right: str) -> str:.
• Scan left from start to end.
• Keep a character only if it also appears in right.
• Do not repeat a character that was already kept.
• The result order must follow the first appearance order in left.
• The comparison is case-sensitive.