code: def recv_file_from_host(src_file, dst_filename, filesize, dst_mode='wb'):
      
      import sys
      import ubinascii
      if HAS_BUFFER:
          try:
              import pyb
              usb = pyb.USB_VCP()
          except:
              try:
                  import machine
                  usb = machine.USB_VCP()
              except:
                  usb = None
          if usb and usb.isconnected():
              # We don't want 0x03 bytes in the data to be interpreted as a Control-C
              # This gets reset each time the REPL runs a line, so we don't need to
              # worry about resetting it ourselves
              usb.setinterrupt(-1)
      try:
          with open(dst_filename, dst_mode) as dst_file:
              bytes_remaining = filesize
              if not HAS_BUFFER:
                  bytes_remaining *= 2  # hexlify makes each byte into 2
              buf_size = BUFFER_SIZE
              write_buf = bytearray(buf_size)
              read_buf = bytearray(buf_size)
              while bytes_remaining > 0:
                  # Send back an ack as a form of flow control
                  sys.stdout.write('\x06')
                  read_size = min(bytes_remaining, buf_size)
                  buf_remaining = read_size
                  buf_index = 0
                  while buf_remaining > 0:
                      if HAS_BUFFER:
                          bytes_read = sys.stdin.buffer.readinto(read_buf, read_size)
                      else:
                          bytes_read = sys.stdin.readinto(read_buf, read_size)
                      if bytes_read > 0:
                          write_buf[buf_index:bytes_read] = read_buf[0:bytes_read]
                          buf_index += bytes_read
                          buf_remaining -= bytes_read
                  if HAS_BUFFER:
                      dst_file.write(write_buf[0:read_size])
                  else:
                      dst_file.write(ubinascii.unhexlify(write_buf[0:read_size]))
                  bytes_remaining -= read_size
          return True
      except:
          return False
docs: Function which runs on the pyboard. Matches up with send_file_to_remote.