class_docstr: This class contains the information about
  the A series of simple Lie algebras.
  ====
docstr: Returns the number of independent generators of A_n
docstr_tok: ["Returns","the","number","of","independent","generators","of","A_n"]
code: def basis(self):
      """
      Returns the number of independent generators of A_n
      """
      n = self.n
      return n**2 - 1
  
file_path: sympy/sympy/liealgebras/type_a.py
imports: from sympy.liealgebras.cartan_type import Standard_Cartan
  from sympy.core.backend import eye
label_desc: Use image node_id 9 for calling the TypeA obj's underlying member method code with example usage: obj.basis() and returns: unknown