input: Write a function to calculate the edit distance between two strings using dynamic programming. Implement this function with the following function header: `def edit_distance(str1, str2):`. Ensure that the function dynamically allocates a table to store and compute intermediate results. The table should be initialized and filled based on comparison of characters from both strings. Finally, return the edit distance, which is the value at the bottom-right corner of the table.
  assert edit_distance("kitten", "sitting") == 3
  assert edit_distance("flaw", "lawn") == 2
  assert edit_distance("horse", "ros") == 3
  assert edit_distance("intention", "execution") == 5
  assert edit_distance("", "a") == 1
  assert edit_distance("a", "") == 1
  assert edit_distance("", "") == 0
output: def edit_distance(str1, str2):
      m, n = len(str1), len(str2)
      dp = [[0] * (n + 1) for _ in range(m + 1)]
      
      for i in range(m + 1):
          for j in range(n + 1):
              if i == 0:
                  dp[i][j] = j
              elif j == 0:
                  dp[i][j] = i
              elif str1[i-1] == str2[j-1]:
                  dp[i][j] = dp[i-1][j-1]
              else:
                  dp[i][j] = 1 + min(dp[i-1][j], dp[i][j-1], dp[i-1][j-1])
      
      return dp[m][n]