I am trying to define variables in Cython part of my code like this

```
a,b,c = var('a,b,c')
```

But in this line I cant import var() function from Sage

```
from sage.calculus.var import var
```

I got this error:

```
$ sage -python real_sage.sage
Compiling ./real_sage.spyx...
Traceback (most recent call last):
File "real_sage.sage", line 6, in <module>
from real_sage import foo
File "real_sage.pyx", line 10, in init real_sage
File "sage/calculus/var.pyx", line 6, in init sage.calculus.var
File "/home/tunamustafakemal/sega/SageMath/local/lib/python2.7/site-packages/sage/symbolic/function_factory.py", line 15, in <module>
from sage.symbolic.function import SymbolicFunction, sfunctions_funcs, \
File "sage/rings/integer.pxd", line 7, in init sage.symbolic.function
File "sage/rings/rational.pxd", line 8, in init sage.rings.integer
File "sage/rings/rational.pyx", line 89, in init sage.rings.rational
File "sage/rings/real_mpfr.pyx", line 1, in init sage.rings.real_mpfr
File "sage/rings/complex_number.pxd", line 6, in init sage.libs.mpmath.utils
File "sage/rings/complex_double.pxd", line 10, in init sage.rings.complex_number
File "sage/rings/complex_double.pyx", line 94, in init sage.rings.complex_double
ImportError: cannot import name complex_number
```

Thanks for any support.