curl -X POST 'https://api.example.com/role-assignments' \
  -H 'Authorization: Bearer YOUR_TOKEN' \
  -H 'Content-Type: application/json' \
  -d '{
    "roleId": "role_456",
    "membershipId": "mem_123"
  }'

const axios = require('axios');

const { data } = await axios.post('https://api.example.com/role-assignments', {
  roleId: 'role_456',
  membershipId: 'mem_123',
}, {
  headers: { 'Authorization': 'Bearer YOUR_TOKEN' },
});

{
  "id": "ra_789",
  "roleId": "role_456",
  "membershipId": "mem_123"
}