code: def _int_check(self, attribute_array, value, irow, key):
          '''Checks if value is valid integer, appends to array if valid, appends
          nan if not'''
          value = value.strip(' ')
          try:
              if value:
                  attribute_array = np.hstack([attribute_array, int(value)])
              else:
                  attribute_array = np.hstack([attribute_array, np.nan])
          except:
              msg = 'Input file format error at line: %d' % (irow + 2)
              msg += ' key: %s' % (key)
              raise ValueError(msg)
          return attribute_arraf _int_check(self, attribute_array, value, irow, key):
          '''Checks if value is valid integer, appends to array if valid, appends
          nan if not'''
          value = value.strip(' ')
          try:
              if value:
                  attribute_array = np.hstack([attribute_array, int(value)])
              else:
                  attribute_array = np.hstack([attribute_array, np.nan])
          except:
              msg = 'Input file format error at line: %d' % (irow + 2)
              msg += ' key: %s' % (key)
              raise ValueError(msg)
          return attribute_array
docs: Checks if value is valid integer, appends to array if valid, appends
          nan if not