Starting with $string = "I swear to tell the whole truth", use the substr_replace() function, to accomplish each of the following (each step should be output to the screen and use the new string generated in the previous step):

1. Insert the word "solemnly " before the word "swear" by counting from the beginning 2. Replace the everything starting at "whole" with "no good ", counting from the end of the string 3. Remove the words "tell the" using a php function to determine that starting position 4. Insert the words "I am up", before "to" using a php function to determine the starting position