**Is your feature request related to a problem? Please describe.** https://docs.starknet.io/documentation/architecture_and_concepts/Smart_Contracts/serialization_of_Cairo_types/#data_types_of_252_bits_or_less **Describe the solution you'd like** Test current behavior and support required field el calc i8, i16, i32, i64, and i128 Negativ value should be 2^{251} + 17*2^{192} + 1 + (negative value) ex -5 should serialise to 2^{251} + 17*2^{192} + 1 - 5