def value_to_bool(config_val, evar):
if not config_val:<EOL><INDENT>return False<EOL><DEDENT>if config_val.strip().lower() == '<STR_LIT:true>':<EOL><INDENT>return True<EOL><DEDENT>else:<EOL><INDENT>return False<EOL><DEDENT>
Massages the 'true' and 'false' strings to bool equivalents.

:param str config_val: The env var value.
:param EnvironmentVariable evar: The EVar object we are validating
    a value for.
:rtype: bool
:return: True or False, depending on the value.