Call subroutines with parentheses but without a leading &. [Call Syntax]
Don't give subroutines the same names as built-in functions. [Homonyms]
Always unpack @_ first. [Argument Lists]
Use a hash of named arguments for any subroutine that has more than three parameters. [Named Arguments]
Use definedness or existence to test for missing arguments. [Missing Arguments]
Resolve any default argument values as soon as @_ is unpacked. [Default Argument Values]
Always return scalar in scalar returns. [Scalar Return Values]
Make list-returning subroutines return the "obvious" value in scalar context. [Contextual Return Values]
When there is no "obvious" scalar context return value, consider Contextual::Return instead. [Multi-Contextual Return Values]
Don't use subroutine prototypes. [Prototypes]
Always return via an explicit return. [Implicit Returns]
Use a bare return to return failure. [Returning Failure]
