INPUT:
- - d -- The domain, either 'real' or 'complex'.
+ - ``d`` -- The domain, either 'real' or 'complex'.
+
+ TESTS:
+
+ With the default 'complex' domain, we don't simplify this::
+
+ sage: (abs(x)^2).simplify()
+ abs(x)^2
+
+ But in the 'real' domain, we do::
+
+ sage: set_simplification_domain('real')
+ 'real'
+ sage: (abs(x)^2).simplify()
+ x^2
+ sage: set_simplification_domain('complex')
+ 'complex'
"""
cmd = 'domain: %s;' % d