def get_default_compartment(model):
default_compartment = '<STR_LIT:c>'<EOL>default_key = set()<EOL>for reaction in model.reactions:<EOL><INDENT>equation = reaction.equation<EOL>if equation is None:<EOL><INDENT>continue<EOL><DEDENT>for compound, _ in equation.compounds:<EOL><INDENT>default_key.add(compound.compartment)<EOL><DEDENT><DEDENT>if None in default_key and default_compartment in default_key:<EOL><INDENT>suffix = <NUM_LIT:1><EOL>while True:<EOL><INDENT>new_key = '<STR_LIT>'.format(default_compartment, suffix)<EOL>if new_key not in default_key:<EOL><INDENT>default_compartment = new_key<EOL>break<EOL><DEDENT>suffix += <NUM_LIT:1><EOL><DEDENT><DEDENT>if None in default_key:<EOL><INDENT>logger.warning(<EOL>'<STR_LIT>'<EOL>'<STR_LIT>'.format(default_compartment))<EOL><DEDENT>return default_compartment<EOL>
Return what the default compartment should be set to.

    If some compounds have no compartment, unique compartment
    name is returned to avoid collisions.