def get_row_section(df, start_value=None, end_value=None):
    """Return a section of rows from a df, based on the start and/or end value to be found in the first column."""
    if start_value:
        first_row_index = df.loc[df.iloc[:, (0)] == start_value].index[0]
    else:
        first_row_index = 0
    if end_value:
        last_row_index = df.loc[df.iloc[:, (0)] == end_value].index[0]
    else:
        last_row_index = len(df.index)
    section = df.iloc[first_row_index:last_row_index + 1, :]
    return section
