Add keywords helpers

Signed-off-by: Vladimir Avdeev <v.avdeev@yadro.com>

src/neofs_testlib/blockchain/multisig.py

@@ -0,0 +1,53 @@
+from typing import List
+
+from neofs_testlib.cli import NeoGo
+
+
+class Multisig:
+    def __init__(self, neogo: NeoGo, invoke_tx_file: str, block_period: int):
+        self.neogo = neogo
+        self.invoke_tx_file = invoke_tx_file
+        self.block_period = block_period
+
+    def create_and_send(
+        self,
+        contract_hash: str,
+        contract_args: str,
+        multisig_hash: str,
+        wallets: List[str],
+        passwords: List[str],
+        address: str,
+        endpoint: str,
+    ) -> None:
+        if not len(wallets):
+            raise AttributeError("Got empty wallets list")
+
+        self.neogo.contract.invokefunction(
+            address=address,
+            rpc_endpoint=endpoint,
+            wallet=wallets[0],
+            wallet_password=passwords[0],
+            out=None if len(wallets) == 1 else self.invoke_tx_file,
+            scripthash=contract_hash,
+            arguments=contract_args,
+            multisig_hash=multisig_hash,
+        )
+
+        if len(wallets) > 1:
+            # sign with rest of wallets except the last one
+            for wallet in wallets[1:-1]:
+                self.neogo.wallet.sign(
+                    wallet=wallet,
+                    input_file=self.invoke_tx_file,
+                    out=self.invoke_tx_file,
+                    address=address,
+                )
+
+            # sign tx with last wallet and push it to blockchain
+            self.neogo.wallet.sign(
+                wallet=wallets[-1],
+                input_file=self.invoke_tx_file,
+                out=self.invoke_tx_file,
+                address=address,
+                rpc_endpoint=endpoint,
+            )