def get_single_col_by_input_type(input_type, column_definition):
  """Returns name of single column.

  Args:
    input_type: Input type of column to extract
    column_definition: Column definition list for experiment
  """

  l = [tup[0] for tup in column_definition if tup[2] == input_type]

  if len(l) != 1:
    raise ValueError('Invalid number of columns for {}'.format(input_type))

  return l[0]