Return a matrix containing all the information present in the
    excel sheet of the specified excel document.

    :arg inputfile: excel document to read
    :arg sheetname: the name of the excel sheet to return

def read_excel_file(inputfile, sheet_name):
    """ Return a matrix containing all the information present in the
    excel sheet of the specified excel document.

    :arg inputfile: excel document to read
    :arg sheetname: the name of the excel sheet to return

    """
    workbook = xlrd.open_workbook(inputfile)
    output = []
    found = False
    for sheet in workbook.sheets():
        if sheet.name == sheet_name:
            found = True
            for row in range(sheet.nrows):
                values = []
                for col in range(sheet.ncols):
                    values.append(sheet.cell(row, col).value)
                output.append(values)
    if not found:  # pragma: no cover
        raise MQ2Exception('Invalid session identifier provided')
    return output