The definition with the "function" keyword doesn't work on plain 'sh'.

See 13a36408

These FP calls seem to be slower than expected.  Using only one doubles
the speed.

Previously, a placeholder was put in the queue ("ZMQdata //" or
"ASAPOdata //"), and replaced by image_read_data_block.  Instead, the
"final" placeholder can be put in the queue already.

Note that ASAP::O, at least, will replace this placeholder with a
filename delivered by the data transport.

With online processing, we might end up with a very long stream.  It
should not be so easily deleted if indexamajig is restarted!