how to define a custom_type_resolver for a nested mapping

[zakerzadeh]

I have a mapping like below

obj = {
'item':{
'item_num':'123',
'item_name':'xyz',
'contacts':{[
{

                    'role':'role1',
                    'name':'name1'
                    }]
            }
        }
    }

I have also defined a custome type_resolver like below

def _custom_type_resolver_tmp(name):
if name == 'item':
return rule_engine.DataType.MAPPING
elif name =='item.item_num':
return rule_engine.DataType.STRING
elif name == 'item.contacts':
return rule_engine.DataType.ARRAY
elif name == 'item.contacts.role':
return rule_engine.DataType.STRING

        raise rule_engine.errors.SymbolResolutionError(name)

but I keep getting an error

'contacts':{[

TypeError: unhashable type: 'list'

wondering if defining such a nested mapping is possible?