code: def add_subject(self, ind_id, sex=None, phenotype=None):
          
  
          self.pedigree_data[ind_id] = len(self.phenotype_data[0])
          if phenotype != None:
              if type(self.phenotype_data) is list:
                  self.phenotype_data[0].append(phenotype)
              else:
                  self.phenotype_data[-1, len(self.individual_mask)] = phenotype
          self.individual_mask.append(0)
  
          if PhenoCovar.sex_as_covariate:
              try:
                  self.covariate_data[0].append(float(sex))
              except Exception, e:
                  raise MalformedInputFile("Invalid setting, %s, for sex in pedigree" % (sex))
docs: Add new subject to study, with optional sex and phenotype
  
          Throws MalformedInputFile if sex is can't be converted to int