Function in scapy-python(ip and mac-address)

The following is my function which throws an error as mentioned below

def get_mac(ip = ""):
    arp_packet = sr(ARP(op = ARP.who_has ,pdst = ip), timeout = 2, verbose = False) 
    mac_address = arp_packet[ARP].hwsrc
    return mac_address

the answer:

IndentationError: unindent does not match any outer indentation level

someone knows why?