'Create the new xmodule but don\'t save it. Returns the new module.
Args:
runtime: :py:class `xblock.runtime` from another xblock in the same course. Providing this
significantly speeds up processing (inheritance and subsequent persistence)
course_key: :py:class `opaque_keys.CourseKey`
block_type: :py:class `string`: the string identifying the xblock type
block_id: the string uniquely identifying the block within the given course
fields: :py:class `dict` field_name, value pairs for initializing the xblock fields. Values
should be the pythonic types not the json serialized ones.'

@strip_key
def create_xblock(self, runtime, course_key, block_type, block_id=None, fields=None, **kwargs):

    store = self._verify_modulestore_support(course_key, 'create_xblock')
    return store.create_xblock(runtime, course_key, block_type, block_id, (fields or {}), **kwargs)
