import json

class DataContractRegistry:
    def __init__(self):
        self._contracts = {}

    def register(self, name: str, schema: dict, version: int = 1):
        self._contracts[name] = {
            "version": version,
            "schema": schema,
        }

    def get(self, name: str):
        return self._contracts.get(name)

    def list_contracts(self):
        return {k: v for k, v in self._contracts.items()}