読み取り用のオープンフラグを定義しない

def print_foo():
  with open("myfile.txt", "r") as myfile:  # "r" フラグの指定は不要です
    content = myfile.read()

  with open(path, "rb") as f:
    for chunk in iter(lambda: f.read(4096), b""):
        hasher.update(chunk)

def print_foo():
  with open("myfile.txt") as myfile:
    content = myfile.read()