Mbpp/771

def check_expression(expr: str) -> bool:
    """
    Checks if the given expression has balanced parentheses, curly braces, and square brackets.
    Returns True if balanced, False otherwise.
    """
    # Map closing brackets to their corresponding opening brackets
    matching = {')': '(', '}': '{', ']': '['}
    stack = []

    for char in expr:
        if char in matching.values():  # opening bracket
            stack.append(char)
        elif char in matching:         # closing bracket
            # If stack is empty or top doesn't match, unbalanced
            if not stack or stack.pop() != matching[char]:
                return False
        # Ignore any other characters (e.g., letters, digits)

    # Expression is balanced only if no unmatched opening brackets remain
    return not stack

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