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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def determine_opening_indent(indent_texts):
    '''Determine the opening indent level for a docstring.

    The opening indent level is the indent level is the first non-zero indent
    level of a non-empty line in the docstring.

    Args:
        indent_texts: The lines of the docstring as an iterable over 2-tuples
            each containing an integer indent level as the first element and
            the text as the second element.

    Returns:
        The opening indent level as an integer.
    '''
    num_lines = len(indent_texts)

    if num_lines < 1:
        return 0

    assert num_lines >= 1

    first_line_indent  = indent_texts[0][0]

    if num_lines == 1:
        return first_line_indent

    assert num_lines >= 2

    second_line_indent = indent_texts[1][0]
    second_line_text   = indent_texts[1][1]

    if len(second_line_text) == 0:
        return first_line_indent

    return second_line_indent