# File lib/hashie/extensions/coercion.rb, line 187
        def build_hash_coercion(type, key_type, value_type)
          key_coerce = fetch_coercion(key_type)
          value_coerce = fetch_coercion(value_type)
          lambda do |value|
            type[value.map { |k, v| [key_coerce.call(k), value_coerce.call(v)] }]
          end
        end