the interface to "where" could use a little rethinking. not all keys are constant string values that are legal identifiers. e.g.

    where([{1 : 'a', 2 : 'b'}, {1 : 'b'}], 1='a')
    SyntaxError: keyword can't be an expression


    where([{1 : 'a', 2 : 'b'}, {1 : 'b'}], **{1:'a'})
    TypeError: where() keywords must be strings

edit: this is based on my own naive "where" implementation, but these are limitations of the language