Fixed warnings

Author: ankane

lib/polars/expr.rb

@@ -3734,15 +3734,7 @@ def xor(other)
     #   # │ [9, 10]   ┆ 3                ┆ false    │
     #   # └───────────┴──────────────────┴──────────┘
     def is_in(other, nulls_equal: false)
-      if other.is_a?(::Array)
-        if other.length == 0
-          other = Polars.lit(nil)._rbexpr
-        else
-          other = Polars.lit(Series.new(other))._rbexpr
-        end
-      else
-        other = Utils.parse_into_expression(other, str_as_lit: false)
-      end
+      other = Utils.parse_into_expression(other)
       _from_rbexpr(_rbexpr.is_in(other, nulls_equal))
     end
     alias_method :in?, :is_in

lib/polars/series.rb

@@ -2144,18 +2144,33 @@ def is_not_nan
 
     # Check if elements of this Series are in the other Series.
     #
+    # @param nulls_equal [Boolean]
+    #   If true, treat null as a distinct value. Null values will not propagate.
+    #
     # @return [Series]
     #
     # @example
     #   s = Polars::Series.new("a", [1, 2, 3])
-    #   s2 = Polars::Series.new("b", [2, 4])
+    #   s2 = Polars::Series.new("b", [2, 4, nil])
     #   s2.is_in(s)
     #   # =>
-    #   # shape: (2,)
+    #   # shape: (3,)
+    #   # Series: 'b' [bool]
+    #   # [
+    #   #         true
+    #   #         false
+    #   #         null
+    #   # ]
+    #
+    # @example
+    #   s2.is_in(s, nulls_equal: true)
+    #   # =>
+    #   # shape: (3,)
     #   # Series: 'b' [bool]
     #   # [
     #   #         true
     #   #         false
+    #   #         false
     #   # ]
     #
     # @example
@@ -2190,7 +2205,7 @@ def is_not_nan
     #   #         true
     #   #         false
     #   # ]
-    def is_in(other)
+    def is_in(other, nulls_equal: false)
       super
     end
     alias_method :in?, :is_in

lib/polars/string_expr.rb

@@ -1474,9 +1474,9 @@ def contains_any(patterns, ascii_case_insensitive: false)
     #   # │ Can you feel the love tonight   ┆ Can me feel the love tonight    │
     #   # └─────────────────────────────────┴─────────────────────────────────┘
     def replace_many(patterns, replace_with, ascii_case_insensitive: false)
-      patterns = Utils.parse_into_expression(patterns, str_as_lit: false, list_as_series: true)
+      patterns = Utils.parse_into_expression(patterns, str_as_lit: false)
       replace_with = Utils.parse_into_expression(
-        replace_with, str_as_lit: true, list_as_series: true
+        replace_with, str_as_lit: true
       )
       Utils.wrap_expr(
         _rbexpr.str_replace_many(