When making a method or function call, there MUST NOT be a space between the method or function name and the opening parenthesis.

In function arguments there must not be arguments with default values before non-default ones. Modifies the signature of functions; therefore risky when using systems (such as some Symfony components) ...

Composite functions are made when the output from one function is used as the input of another function. The names of the functions are written next to each other, with the function that is used first ...