Matching against objects derived from base collection types

I would like to use this library to match against values derived like collections.MutableSequence and collections.MutableMapping. For example:

`
import collections

import jmespath

class MySequence( collections.MutableSequence ):

def __init__( self, data ):
self.data = data

def __delitem__( self, index ):
del self.data[index]

def __getitem__( self, index ):
return self.data[index]

def __len__( self ):
return len( self.data )

def __setitem__( self, index, value ):
self.data[index] = value

def insert( self, index, value ):
self.data.insert( index, value )

data = [
{"name": "Seattle", "state": "WA"},
{"name": "New York", "state": "NY"},
{"name": "Bellevue", "state": "WA"},
{"name": "Olympia", "state": "WA"}
]

print jmespath.compile( '[0]' ).search( data ) # --> {'state': 'WA', 'name': 'Seattle'}
print jmespath.compile( '[0]' ).search( MySequence( data ) ) # --> None
`
It seems like this should be doable by changing all instances of isinstance( foo, list ) to isinstance( foo, collections.MutableSequence ), as this will return True for the default list type.