parameters: (self, atom)
return_statement: return self.full_atoms[atom].mass()
docstring: Returns mass of atom (0-indexed, includes dummies)
  
          >>> print(H2OH2O.fmass(4))
          15.9949146196
docstring_summary: Returns mass of atom (0-indexed, includes dummies)
docstring_tokens: Returns mass of atom ( 0 - indexed includes dummies )
function: def fmass(self, atom):
          """Returns mass of atom (0-indexed, includes dummies)
  
          >>> print(H2OH2O.fmass(4))
          15.9949146196
  
          """
          return self.full_atoms[atom].mass()
function_tokens: def fmass ( self , atom ) : return self . full_atoms [ atom ] . mass ( )