new_contents: import yaml
  from prf.state import State
  from prf.point import Point, Curve
  from prf.impeller import Impeller
  
  
  def load(file):
      """Load impeller from yaml file.
  
      Spreadsheet or other file types should be converted to yaml files before
      loading.
  
  
      """
      with open(file, 'r') as f:
          input_data = yaml.load(f)
  
      units = {}
  
      for k, v in input_data['units'].items():
          units[k + '_units'] = v
  
      if units['T_units'] == 'C':
          units['T_units'] = 'degC'
  
      flow_v = input_data['curve']['flow']
      head = input_data['curve']['head']
      eff = input_data['curve']['eff']
      ps = input_data['suction']['ps']
      Ts = input_data['suction']['Ts']
      composition = input_data['composition']
      speed = input_data['speed']
      D = input_data['geometry']['D']
      b = input_data['geometry']['b']
  
      suc = State.define(p=ps, T=Ts, fluid=composition, **units)
  
      curve = Curve([
          Point(suc=suc, flow_v=f, head=h, eff=e, speed=speed, **units)
          for f, h, e in zip(flow_v, head, eff)
      ])
  
      imp = Impeller(curve, b=b, D=D)
  
      return imp
  
subject: Add function to load from yaml.