How to create this function without using .spllit

def insert_substrings_into_string(s, substrs):
“”"(string, string) → string
Returns the string s with placeholder characters replaced by substrings in substrs.

>>>insert_substrings_into_string("I like big %0 and I cannot lie", "macs")
'I like big macs and I cannot lie'


for x in range(0,len(sub)):
    find = '%' + str(x)
    s = s.replace(find, sub[x].strip())
return s

Im confused… what is your program meant to do?