print_occurs: The third task is to read in a motif from the keyboard, which is a short
pattern of DNA. You will write a function that will find all occurrences of the motif in
the entire input sequence. For example, if the DNA sequence is
ACGTTTACGTTACGTC and the motif is ACG, your program should report that the
motif is found 3 times in the DNA sequence, at positions 0, 6, and 11 of the DNA
sequence. You will write a function called print_occurs that will receive two parameters.
The first parameter is a string representing a longer DNA sequence, the second parameter
is a string containing a shorter motif. The function should print the positions of each
occurrence of the motif in the longer sequence. If the motif is not found at all, the
function should print an appropriate message. The function should not change either
parameter.