# your code goes here
import re
def Rep(str,chr,Rchr):
if chr in str:
str1 = Rchr if chr else None
result = re.sub(chr, str1, str)
print(result)
else:
print("character is not present in the string to replace")
Rep("Hihwru","wr","oware")
IyB5b3VyIGNvZGUgZ29lcyBoZXJlCgppbXBvcnQgcmUKCmRlZiBSZXAoc3RyLGNocixSY2hyKToKICAgIGlmIGNociBpbiBzdHI6CiAgICAgICAgc3RyMSA9IFJjaHIgaWYgY2hyIGVsc2UgTm9uZQogICAgICAgIHJlc3VsdCA9IHJlLnN1YihjaHIsIHN0cjEsIHN0cikKICAgICAgICBwcmludChyZXN1bHQpCiAgICBlbHNlOgogICAgICAgIHByaW50KCJjaGFyYWN0ZXIgaXMgbm90IHByZXNlbnQgaW4gdGhlIHN0cmluZyB0byByZXBsYWNlIikKClJlcCgiSGlod3J1Iiwid3IiLCJvd2FyZSIp