def _lease_valid(self, lease):
if not lease.exist:<EOL><INDENT>return None<EOL><DEDENT>if lease.has_env:<EOL><INDENT>return lease.uuid_path<EOL><DEDENT>else:<EOL><INDENT>self._release(lease)<EOL>return None<EOL><DEDENT>
Check if the given lease exist and still has a prefix that owns it.
If the lease exist but its prefix isn't, remove the lease from this
store.

Args:
    lease (lago.subnet_lease.Lease): Object representation of the
        lease

Returns:
    str or None: If the lease and its prefix exists, return the path
        to the uuid of the prefix, else return None.