def generate_vm_name_str(vms):
    """ Generate a str with concatenation of given list of vm name """
    # vms is a list of vm_name
    # example: vms=["vm1", "vm2"]
    # the return value is a string like this "vm1,vm2""
    res = ""
    for vm in vms:
        # vm[0] is vm_uuid, vm has format (vm_uuid)
        res = res + vm
        res = res + ","

    if res:
        res = res[:-1]

    return res