The string manipulation functions in R can be used instead of regular expression functions for finding, changing, and extracting substrings from strings. These functions include: strsplit () to divide a string up into pieces, substr () to extract a portion of a string, paste () to glue together multiple strings, and nchar (), which returns the number of characters in a string. Write your own version of get Boundary () (see Section 3.5.2) using these functions to extract the boundary string from the Content-Type. Debug your function with the messages in sample Email.