Migrate most uses of if type() to if isinstance()

Also convert those checks to use abcs instead of dict and list.

Make a sentinel class for strategies to report when they've reache the end

lib/ansible/plugins/lookup/csvfile.py

@@ -19,6 +19,7 @@ __metaclass__ = type
 
 import codecs
 import csv
+from collections import MutableSequence
 
 from ansible.errors import AnsibleError
 from ansible.plugins.lookup import LookupBase
@@ -102,7 +103,7 @@ class LookupModule(LookupBase):
             lookupfile = self.find_file_in_search_path(variables, 'files', paramvals['file'])
             var = self.read_csv(lookupfile, key, paramvals['delimiter'], paramvals['encoding'], paramvals['default'], paramvals['col'])
             if var is not None:
-                if type(var) is list:
+                if isinstance(var, MutableSequence):
                     for v in var:
                         ret.append(v)
                 else:

lib/ansible/plugins/lookup/dig.py

@@ -22,11 +22,12 @@ from ansible.plugins.lookup import LookupBase
 import socket
 
 try:
+    import dns.exception
+    import dns.name
     import dns.resolver
     import dns.reversename
     from dns.rdatatype import (A, AAAA, CNAME, DLV, DNAME, DNSKEY, DS, HINFO, LOC,
             MX, NAPTR, NS, NSEC3PARAM, PTR, RP, SOA, SPF, SRV, SSHFP, TLSA, TXT)
-    import dns.exception
     HAVE_DNS = True
 except ImportError:
     HAVE_DNS = False
@@ -70,7 +71,7 @@ def make_rdata_dict(rdata):
         for f in fields:
             val     = rdata.__getattribute__(f)
 
-            if type(val) == dns.name.Name:
+            if isinstance(val, dns.name.Name):
                 val = dns.name.Name.to_text(val)
 
             if rdata.rdtype == DLV and f == 'digest':

lib/ansible/plugins/lookup/ini.py

@@ -17,9 +17,10 @@
 from __future__ import (absolute_import, division, print_function)
 __metaclass__ = type
 
-from io import StringIO
 import os
 import re
+from collections import MutableSequence
+from io import StringIO
 
 from ansible.errors import AnsibleError
 from ansible.module_utils.six.moves import configparser
@@ -110,7 +111,7 @@ class LookupModule(LookupBase):
             else:
                 var = self.read_ini(path, key, paramvals['section'], paramvals['default'], paramvals['re'])
             if var is not None:
-                if type(var) is list:
+                if isinstance(var, MutableSequence):
                     for v in var:
                         ret.append(v)
                 else: