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Is there a way to perform a "literal replacing" in SymPy, which matches exactly the pattern?

For example, for the expression `exp(I*theta)+exp(-I*theta)`

, I would like to replace only exp(I*t) to zero without replacing exp(-I*t)

A minimal example would be

```
from sympy import *
f=exp(I*t)+exp(-I*t)
```

Clearly, `subs`

will not work

```
f.subs((exp(I*t),0))
```

because it also replaces `exp(-I*t)`

with infinity.

### >Solution :

You can use the `xreplace`

method:

```
f.xreplace({exp(I*t):0})
```

Returns:

```
exp(-t*I)
```

Here is the documentation for reference.