code: def inasafe_place_value_percentage(number, total, feature, parent):
      
      _ = feature, parent  # NOQA
      if number < 0:
          return None
      percentage_format = '{percentage}%'
      percentage = round((float(number) / float(total)) * 100, 1)
      return percentage_format.format(percentage=percentage)
docs: Given a number and total, it will return the percentage of the number
      to the total.
  
      For instance:
      *   inasafe_place_value_percentage(inasafe_analysis_summary_field_value(
          'female_displaced'), inasafe_analysis_summary_field_value('displaced'))
          -> will calculate the percentage of female displaced count to total
          displaced count.
  
      It also can be used by pure number (int, float).