# Substitution using function-call syntax and unnamed arguments has been removed. You can use named arguments instead

I am trying to evaluate a definite integral whose upper limit is a variable. Here are the lines,

```
var('x')
var('x_')
assume(x,'real',x>0)
assume(x_,'real',x_>=0)
f(x) = integrate(1/sqrt(0.3*(1+x_)^3+0.7),x_,0,x)
```

And then I want to plot f as a function of x,

```
plot(f(x),(x,0.1,10))
```

This produces an error with the following error message,

```
verbose 0 (3897: plot.py, generate_plot_points) WARNING: When plotting, failed to evaluate function at 200 points.
verbose 0 (3897: plot.py, generate_plot_points) Last error message: 'Substitution using function-call syntax and unnamed arguments has been removed. You can use named arguments instead, like EXPR(x=..., y=...)'
```

Can anyone suggest what I'm doing wrong?

Thank you.

This looks like a very strange bug. The workaround

`plot(lambda x0: f(x0), (x,0.1,10))`

works in the meantime.Please report the issue at https://github.com/sagemath/sage/issues

I reported the issue (issue #37776). But on the GitHub issues page can't seem to see what I typed under the headings, "Steps To Reproduce", "Expected Behavior" and "Actual Behavior". Do I need to do anything else?

Yes. issue #37776 is empty. Please edit it and add the content.

Hi Max,

I have added some content to the issue (https://github.com/sagemath/sage/issu...).

Thank you for your guidance.