text: class Mass:
      AAMass = {'A' : 71.0371138,
                'C_': 103.00918,
                'C' : 160.0306481,
                'D' : 115.0269429,
                'E' : 129.042593,
                'F' : 147.0684139,
                'G' : 57.0214637,
                'H' : 137.0589118,
                'I' : 113.0840639,
                'K' : 128.094963,
                'L' : 113.0840639,
                'M' : 131.0404846,
                'N' : 114.0429274,
                'P' : 97.0527638,
                'Q' : 128.0585774,
                'R' : 156.101111,
                'S' : 87.0320284,
                'T' : 101.0476784,
                'V' : 99.0684139,
                'W' : 186.0793129,
                'Y' : 163.0633285
                }
  
      ProtonMass = 1.0072766  # H+
      IsotopeMass = 1.003
  
      ElementMass = {'C': 12.,
                     'H': 1.0078250321,
                     'O': 15.9949146221,
                     'N': 14.0030740052,
                     }
  
      CompoundMass = {
          'H2O': ElementMass['H'] * 2 + ElementMass['O'],
          'NH3': ElementMass['N'] + ElementMass['H'] * 3,
      }
  
      ModificationMass = {'Carbamidomethyl'   : 57.0214637,
                          'Oxidation'         : ElementMass['O'],
                          'C[Carbamidomethyl]': 57.0214637,
                          'M[Oxidation]'      : 16.,
                          '1'                 : 147.0353992,  # M[16]
                          '2'                 : 167.03203,  # S[80]
                          '3'                 : 181.04768,  # T[80]
                          '4'                 : 243.06333,  # Y[80]
                          }
  
  # C[Carbamidomethyl] = 103.00918 + 57.0214637
  # M[Oxidation] = 131.04048 + 16
  
  # H2O + H+ -> 'e'
  # H+ -> 'h'
  