Arrays and if macros

How do I make sure that an array does not have more than a set amount of a variable? I've already looked at the Sugarcube 2 library and the count and includes macros don't seem to work with if macros.

<<if $mapArray.count("3") gt 7>>
<<set $mapArray.("3") to 7>>
<</if>>

Please let me know what I'm doing wrong.