the place that does not require spaces is the equation itself.
a = 1 + 2
or
a = 1+2
will return the same value.
I think this is where the mix up is happening while it may need to be fixed in documentation due to a typo most likely (I have not really looked personally to verify) this was the original intent as there was a time where the equation required spacing as well if I remember correctly.
As long as I can remember though variable assignment has always required spaces before and after the "=" sign as a rule. Interesting to note that the space after the "=" sign does not seem to be required as was mentioned but as a rule I would add it to stay on the safe side of things as this may cause something else to go wrong within your program if it is a bug of some sort.
Hope this helps.
Where I buy my ESP8266 boards from... (Banggood)