"hold" is going to be a rather tenuous construction anyway, because there
are going to be various places where the expression will be "deholded" and
there is very poor control over where those hold removals occur. It's not a
very well-supported feature -- mainly because its semantic meaning is m
Whoops, I have sent an old version of the function by mistake.
I meant to send
```
def Dt(expression1):
if len(expression1.args()) == 1 \
and expression1.args()[0]==expression1:
# if the expression has only one variable
# and that variable is the entire expression
return
Thank you very much for your reply, i learned a lot
My initial intention when asking the prior question was to define a
function where some evaluations would return itself, while other
evaluations would not. Such as
```
def f(x):
if x%2==0:
return hold(f(x))
else:
retu
Dear erentar,
There are two types of objects involved here: "symbolic functions" that
live as objects in SR and "python functions" which are part of python
itself. "hold" is only a directive that applies to symbolic expressions,
whereas "def" defines a python function. Hence, the "hold" directi
