als the end of the data lines, at which point a new regular
expression is read. The regular expressions are given enclosed in any
non-alphanumeric delimiters other than backslash, for example:
<pre>
  /(a|bc)x+yz/
</pre>
White space before the initial delimiter is ignored. A regular expression may
be continued over several input lines, in which case the newline characters are
included within it. It is possible to include the delimiter within the pattern
by escaping it, for example
<pre>
  /abc\/def/
</pre>
