input: Write a function to compute the edit distance between two strings in Python. If the two strings are empty, return 0.
  assert editDistance("kitten", "sitting", 6, 7)==3
  assert editDistance("intention", "execution", 9, 9)==5
  assert editDistance("cat", "cut", 3, 3)==1
  assert editDistance("", "", 0, 0)==0
  assert editDistance("park", "", 4, 0)==4
output: def editDistance(str1, str2, m, n):
      if m == 0:
          return n
      if n == 0:
          return m
      if str1[m-1] == str2[n-1]:
          return editDistance(str1, str2, m-1, n-1)
      return 1 + min(editDistance(str1, str2, m, n-1),    # Insert
                     editDistance(str1, str2, m-1, n),    # Remove
                     editDistance(str1, str2, m-1, n-1)) # Replace