Feat: remove set_render("txt") in doctest

mapytex/calculus/API/__init__.py

@@ -11,7 +11,6 @@ Generate and compute like a student!
 
 :example:
 
->>> Expression.set_render("txt")
 >>> e = Expression.from_str("2+3*4")
 >>> e_simplified = e.simplify()
 >>> print(e_simplified)

mapytex/calculus/API/expression.py

@@ -24,7 +24,6 @@ class Expression(object):
 
     :example:
 
-    >>> Expression.set_render("txt")
     >>> e = Expression.from_str("2+3*4")
     >>> e2 = e.simplify()
     >>> print(e2)
@@ -51,7 +50,6 @@ class Expression(object):
         :param render: render name (txt or tex)
 
         :example:
-        >>> Expression.set_render('txt')
         >>> e = Expression.from_str("2+3*4")
         >>> print(e)
         2 + 3 * 4

mapytex/calculus/API/tokens/token.py

@@ -29,7 +29,6 @@ class Token(object):
     def random(cls):
         raise NotImplemented
 
-
     @classmethod
     def set_render(cls, render):
         """ Define default render function