input: Write a python function to find the character with the highest frequency in a given string.
  assert find_highest_freq_char("Sample string") == (' ', 2)
  assert find_highest_freq_char("hello world") == ('l', 3)
  assert find_highest_freq_char("aabbcc") == ('a', 2)
output: def find_highest_freq_char(s):
      from collections import Counter
      count = Counter(s)
      most_common = count.most_common(1)[0]
      return most_common