fix py2 issue

doc/api-example.rst

@@ -2,8 +2,6 @@
 ``sourmash`` Python examples
 ============================
 
->>> from __future__ import print_function
-
 A very simple example: two k-mers
 ---------------------------------
 
@@ -67,12 +65,13 @@ to ignore non-ACTGN characters.
 
 And now the estimators can be compared against each other:
 
+>>> import sys
 >>> for i, e in enumerate(estimators):
-...    print(genomes[i][:20], end=' ')
+...    sys.stdout.write(genomes[i][:20] + ' ')
 ...    for j, e2 in enumerate(estimators):
 ...       x = e.jaccard(estimators[j])
-...       print(round(x, 3), end=' ')
-...    print('')
+...       sys.stdout.write(str(round(x, 3)) + ' ')
+...    sys.stdout.write('\n')
 data/GCF_000005845.2 1.0 0.0 0.0 
 data/GCF_000006945.1 0.0 1.0 0.0 
 data/GCF_000783305.1 0.0 0.0 1.0