code: def map_columns(col):
      
      if col.startswith('7'):
          # spectral data
          try:
              return VARIABLE_MAP[col]
          except KeyError:
              return col
      try:
          variable_name = VARIABLE_MAP[col[:3]]
          variable_number = col[3:]
          return variable_name + '_' + variable_number
      except KeyError:
          return col
docs: Map data element numbers to pvlib names.
  
      Parameters
      ----------
      col: str
          Column label to be mapped.
  
      Returns
      -------
      str
          The pvlib label if it was found in the mapping,
          else the original label.