"Rename" target mutation

[sobolevn]

Related to #81

The same problem I have with other attributes in dicts that must be renamed before actually working with them.

def tranform_data(webhook):
    return glom(webhook_data, (
            Assign('project.id', Spec('project.uid')),

            # Issue tranformation:
            Assign('object_attributes.id', Spec('object_attributes.uid')),
            Assign('issue', Spec('object_attributes')),
        ))

And then usage:

webhook_data = {'project': {'uid': 1}, 'object_attributes': {'uid': 2}}
modified = tranform_data(webhook_data)
# =>  {'project': {'id': 1, 'uid': 1}, 'object_attributes': {'id': 2, 'uid': 2}, 'issue': {'id': 2, 'uid': 2}}

That can quickly become to complex inside, when we really want ot just rename the key.
So, that why I suggest to make Rename mutation.

That's how it would work:

def tranform_data(webhook):
    return glom(webhook_data, (
            Rename('project.id', Spec('project.uid')),

            # Issue tranformation:
            Rename('object_attributes.id', Spec('object_attributes.uid')),
            Rename('issue', Spec('object_attributes')),
        ))

webhook_data = {'project': {'uid': 1}, 'object_attributes': {'uid': 2}}
modified = tranform_data(webhook_data)
# =>  {'project': {'id': 1}, 'issue': {'id': 2}}