@classmethod
def get_first_line(cls, lines):
    """Get the line number of the first non-empty line in a list.

        Args:

            lines (list of str): A list of text.

        Returns:

            int: If non-empty line exists return the line number, otherwise 0.
        """
    for num, line in enumerate(lines):
        if line.strip():
            return num
    return 0
