"""Check if a string contains balanced parentheses.

This function validates whether the input string contains balanced pairs of parentheses.
It ensures that every opening parenthesis '(' has a corresponding closing parenthesis ')'
and that the parentheses are properly nested.

Args:
    s (str): The string to be validated.

Returns:
    bool: True if the string contains balanced parentheses, False otherwise.

Examples:
    >>> check_valid('')
    True
    >>> check_valid('()')
    True
    >>> check_valid('(())')
    True
    >>> check_valid('()()')
    True
"""
You should write code starting with:
def check_valid(s: str) -> bool:
    pass

