code: def import_calculations_from_file( filename ):
      
      calcs = {}
      with open( filename, 'r' ) as stream:
          docs = yaml.load_all( stream, Loader=yaml.SafeLoader )
          for d in docs:
              stoichiometry = Counter()
              for s in d['stoichiometry']:
                  stoichiometry.update( s )
              calcs[ d['title'] ] = Calculation( title=d['title'], 
                                                 stoichiometry=stoichiometry, 
                                                 energy=energy_string_to_float( d['energy'] ) )
      return calcs
docs: Construct a list of Calculation objects by reading a YAML file.
      Each YAML document should include 'title', 'stoichiometry', and 'energy' fields. e.g.::
  
          title: my calculation
          stoichiometry:
              - A: 1
              - B: 2
          energy: -0.1234 eV
  
      Separate calculations should be distinct YAML documents, separated by `---`
      
      Args:
          filename (str): Name of the YAML file to read.
  
      Returns:
          (dict(vasppy.Calculation)): A dictionary of Calculation objects. For each Calculation object, the 'title' field from the YAML input is used as the dictionary key.