input: Write a function to filter names with exactly 10 characters.
  assert filter_names(['Johanna', 'George', 'John', 'Bobby', 'Steven'])==['Johanna', 'Steven']
  assert filter_names(['Alexandria', 'Jonathan', 'Isabella', 'Christopher'])==['Alexandria', 'Jonathan', 'Isabella']
  assert filter_names(['Nick', 'Jim', 'Alexander', 'Elizabeth'])==[]
output: def filter_names(names):
      return [name for name in names if len(name) == 10]