The NCBI allows users to access more records (10 per second) if they register for and use an API key. This function allows users to set this key for all calls to rentrez functions during a particular R session. See the vignette section "Using API keys" for a detailed description.
set_entrez_key(key)
character. Value to set ENTREZ_KEY to (i.e. your API key).
A logical of length one, TRUE is the value was set FALSE if not. value is returned inside invisible(), i.e. it is not printed to screen when the function is called.