docs: def _check_password(password):
          """Check the strength of a password.
          A password is considered strong if
              8 characters length or more
              1 digit or more
              1 uppercase letter or more
              1 lowercase letter or more
              1 symbol (excluding whitespace characters) or more
  
          Parameters
          ----------
          password: str
  
          Returns
          -------
          bool
              True if the password is strong enough, False otherwise.
          """
          # Check the length.
          length_error = len(password) < 8
  
          # Search for digits.
          digit_error = re.search(r'\d', password) is None
  
          # Search for uppercase letters.
          uppercase_error = re.search(r'[A-Z]', password) is None
  
          # Search for lowercase letters.
          lowercase_error = re.search(r'[a-z]', password) is None
  
          # Search for symbols (excluding whitespace characters).
          symbol_error = re.search(r'[^A-Za-z\d\s]', password) is None
  
          return not (length_error or digit_error or uppercase_error or\
                      lowercase_error or symbol_error)