the hint they gave was this function modifies the original list and does not return anything. We also need to take into account when we send an empty dictionary.

def letter_grades(adict): """ Modifies the new dictionary to replace numerical grades with letter grades. The dictionary adict has netids for keys and numbers 0-100 for values. These represent the grades that the students got on the exam. This function replaces all of the numerical grades with letter grades (strings) for values. Our cut-off is 90 for an A, 80 for a B, 70 for a C, 60 for a D. Anything below 60 is an F. Examples: If a = {'wmw2' : 55, 'abc3' : 90, 'jms45': 86}, letter_grades(a) changes a to {'wmw2' : 'F, 'abc3' : 'A', 'jms45': 'B'}. If a = {} letter_grades(a) changes a to {} Parameter adict: the dictionary of grades Precondition: adict is dictionary mapping strings to ints """ pass