channel		channel
header		initial header bytes

Read takes binary data from the specified channel and returns a view structure extracted from that data.

The data read must have the proper format, created either with {Metakit} or with one of the {emit}, {save}, or {write} operators.

When no header is specified, the first 8 bytes are read to determine exactly how many more bytes follow. This avoids reading to EOF and means that no data past the end of the saved view will be consumed.

If a non-empty header is given, it will be used as if it had been read just before the rest of the data. This can also be used to force reading to EOF by specifying dummy data, such as "########".

(read is defined in Ratcl)