'Initialze internal state.
Eval the string value and save the result.
Args:
value: String to compile as a regular expression.
key: The YAML field name.
Raises:
InvalidCodeInConfiguration: if the code could not be evaluated, or
the evalauted method is not callable.'

def __init__(self, value, key):

    self.value = value
    try:
        self.method = eval(value, _global_temp_globals)
    except Exception as err:
        raise bulkloader_errors.InvalidCodeInConfiguration(('Invalid    code    for    %s.    Code:    "%s".    Details:    %s' % (key, value, err)))
    if (not callable(self.method)):
        raise bulkloader_errors.InvalidCodeInConfiguration(('Code    for    %s    did    not    return    a    callable.        Code:    "%s".' % (key, value)))
    self.supports_bulkload_state = False
    try:
        argspec = inspect.getargspec(self.method)
        if ('bulkload_state' in argspec[0]):
            self.supports_bulkload_state = True
    except TypeError:
        pass
