Prints header to f (will write header based on verbose)

        :param f: stream to print output
        :param verbose: print all data or only the most important parts?

def print_header(self, f=sys.stdout, verbose=False):
        """Prints header to f (will write header based on verbose)

        :param f: stream to print output
        :param verbose: print all data or only the most important parts?
        """
        self.var_count = 2 + len(self.covar_labels)

        if verbose:
            header = [
                "Chr",
                "Pos",
                "RSID",
                "Phenotype",
                "N",
                "Ref_allele",
                "Eff_allele",
                "Eff_Allele_Freq",
                "P-Value",
                "LM_PValue"
            ]
            for var in ["Intercept","Geno"] + self.covar_labels:
                for t in ["mean", "mean_stder", "mean_pval", "var", "var_stder", "var_pval"]:
                    header.append("%s_%s" % (var.lower(), t))
            print >> f, "\t".join(header)
        else:
            print >> f, "\t".join([
                "Chr",
                "Pos",
                "RSID",
                "Phenotype",
                "N",
                "Ref_allele",
                "Eff_allele",
                "Eff_Allele_Freq",
                "P-Value",
                "geno_mean",
                "geno_mean_stderr",
                "geno_mean_pval",
                "geno_var",
                "geno_var_stderr",
                "geno_var_pval",
            ])