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