Write a function named Countstr that operates over a list which includes a series of strings. The function takes a string and outputs the number of occurrences of that string in the given list.

For example: Assume that dlist is a list that the user wants to search for the number of occurrences for the string synth. dlist=[synthetic,polymer,synthesizer,abaqus,python,synths,macro] The function that you prepare will search for synth in each element of the list. The string synth has 3 occurrences in the list [synthetic,polymer,synthesizer,abaqus,python,synths,macro].

Then it will report the number of occurrences as follows: The string synth has 3 occurrences in the list [synthetic,polymer,synthesizer,abaqus,python,synths,macro].