If all in list == something

Use:

all( type(i) is int for i in lst )

Example:

In [1]: lst = range(10)
In [2]: all( type(i) is int for i in lst )
Out[2]: True
In [3]: lst.append('steve')
In [4]: all( type(i) is int for i in lst )
Out[4]: False

[Edit]. Made cleaner as per comments.