:cacheThe :cache header argument controls the use of
in-buffer caching of the results of evaluating code blocks. It
can be used to avoid re-evaluating unchanged code blocks. This
header argument can have one of two values: yes or
no.
no The default. No caching takes place, and
the code block will be evaluated every time it is called.yes Every time the code block is run a SHA1
hash of the code and arguments passed to the block will be
generated. This hash is packed into the #+results:
line and will be checked on subsequent executions of the code
block. If the code block has not changed since the last time it
was evaluated, it will not be re-evaluated.