def nCr(n, r):
    return factorial(n) / ( factorial(n-r) * factorial(r))
Refresh the node's cached clean steps from the booted agent.
dataset/ETHPy150Open kdart/pycopia/core/pycopia/combinatorics.py/nCr--crossover with--dataset/ETHPy150Open openstack/ironic/ironic/drivers/modules/agent_base_vendor.py/BaseAgentVendor._refresh_clean_steps