The read4 API is already defined for you.
def read4(buf4: List[chr]) -> int:
# Below is an example of how the read4 API can be called.
file = File("abcdefghijk") # File is "abcdefghijk", initially file pointer (fp) points to 'a'
buf4 = [' '] * 4 # Create buffer with enough space to store characters
read4(buf4) # read4 returns 4. Now buf = ['a','b','c','d'], fp points to 'e'
read4(buf4) # read4 returns 4. Now buf = ['e','f','g','h'], fp points to 'i'
read4(buf4) # read4 returns 3. Now buf = ['i','j','k',...], fp points to end of file
def read(self, buf: List[str], n: int) -> int:
buf4 = [' '] * 4
i4 = 0 # buf4's index
n4 = 0 # buf4's size
i = 0 # buf's index
while i < n:
if i4 == n4: # all characters in buf4 are consumed
i4 = 0 # reset buf4's index
n4 = read4(buf4) # read 4 (or less) chars from file to buf4
if n4 == 0: # reach the EOF
buf[i] = buf4[i4]
i += 1
i4 += 1