def calculate_storage(filesize):
    block_size = 4096
    # Use floor division to calculate how many blocks are fully occupied
    full_blocks = filesize // block_size
    if full_blocks == 0 and filesize != 0:
      full_blocks = 1
    # Use the modulo operator to check whether there's any remainder
    partial_block_remainder =  (full_blocks * block_size) % filesize
    # Depending on whether there's a remainder or not, return the right number.
    if partial_block_remainder > 0:
        return calculate_storage(partial_block_remainder) + (full_blocks * block_size)
    return full_blocks * block_size

print(calculate_storage(1))    # Should be 4096
print(calculate_storage(4096)) # Should be 4096
print(calculate_storage(4097)) # Should be 8192
print(calculate_storage(6000)) # Should be 8192