def normalize_cutoff(model, zero_cutoff=None):
if zero_cutoff is None:<EOL><INDENT>return model.tolerance<EOL><DEDENT>else:<EOL><INDENT>if zero_cutoff < model.tolerance:<EOL><INDENT>raise ValueError(<EOL>"<STR_LIT>"<EOL>"<STR_LIT>"<EOL>)<EOL><DEDENT>else:<EOL><INDENT>return zero_cutoff<EOL><DEDENT><DEDENT>
Return a valid zero cutoff value.