### 2.54.3 List of variables and of expressions : `lvar`

`lvar` takes as argument an expression.
`lvar` returns a list of variable names and non-rationnal expressions such that it’s argument is a rational fraction with respect to the variables and expressions of the list.
Input :

`lvar(x*y*sin(x)```^```2)`

Output :

`[x,y,sin(x)]`

Input :

`lvar(x*y*sin(x)```^```2+ln(x)*cos(y))`

Output :

`[x,y,sin(x),ln(x),cos(y)]`

Input :

`lvar(y+x*sqrt(z)+y*sin(x))`

Output :

`[x,y,sqrt(z),sin(x)]`