diff --git a/midas/checker/frame_methods.py b/midas/checker/frame_methods.py
new file mode 100644
index 0000000..60c6eb1
--- /dev/null
+++ b/midas/checker/frame_methods.py
@@ -0,0 +1,124 @@
+from __future__ import annotations
+
+from typing import TYPE_CHECKING, Optional, Protocol
+
+from midas.ast.location import Location
+from midas.checker.reporter import FileReporter
+from midas.checker.types import (
+    ColumnType,
+    DataFrameType,
+    Function,
+    Type,
+    UnknownType,
+    unfold_type,
+)
+
+if TYPE_CHECKING:
+    from midas.checker.frames import FrameManager
+    from midas.checker.python import PythonTyper, TypedExpr
+
+
+class FrameMethod(Protocol):
+    @property
+    def __name__(self) -> str: ...
+    def __call__(
+        self,
+        typer: PythonTyper,
+        manager: FrameManager,
+        reporter: FileReporter,
+        location: Location,
+        frame: DataFrameType,
+        positional: list[TypedExpr],
+        keywords: dict[str, TypedExpr],
+    ) -> Type: ...
+
+
+FRAME_METHODS: dict[str, FrameMethod] = {}
+
+
+def frame_method(*names: str):
+    def wrapper(func: FrameMethod):
+        names_: tuple[str, ...] = names
+        if len(names_) == 0:
+            names_ = (func.__name__,)
+        for name in names_:
+            FRAME_METHODS[name] = func
+        return func
+
+    return wrapper
+
+
+@frame_method("add", "__add__")
+def add(
+    typer: PythonTyper,
+    manager: FrameManager,
+    reporter: FileReporter,
+    location: Location,
+    frame: DataFrameType,
+    positional: list[TypedExpr],
+    keywords: dict[str, TypedExpr],
+) -> Type:
+    new_columns: list[DataFrameType.Column] = []
+
+    by_name: dict[str, DataFrameType.Column] = {}
+    frame2: Optional[DataFrameType] = None
+    if len(positional) != 0:
+        other: Type = positional[0][1]
+        unfolded_other: Type = unfold_type(other)
+        if isinstance(unfolded_other, DataFrameType):
+            frame2 = unfolded_other
+            by_name = {col.name: col for col in frame2.columns if col.name is not None}
+
+    in_frame1: set[str] = set()
+    for column in frame.columns:
+        if column.name is not None:
+            in_frame1.add(column.name)
+
+        col_type1: Type = column.type
+        col_type: Type = ColumnType(type=UnknownType())
+        if column.name in by_name:
+            column2 = by_name[column.name]
+            col_type2: Type = column2.type
+            if manager.types.are_equivalent(col_type2, col_type1):
+                col_type = col_type1
+
+        new_column = DataFrameType.Column(
+            index=column.index,
+            name=column.name,
+            type=col_type,
+        )
+        new_columns.append(new_column)
+
+    if frame2 is not None:
+        for column in frame2.columns:
+            if column.name in in_frame1:
+                continue
+            new_columns.append(
+                DataFrameType.Column(
+                    index=len(new_columns),
+                    name=column.name,
+                    type=ColumnType(type=UnknownType()),
+                )
+            )
+
+    signature = Function(
+        args=[
+            Function.Argument(
+                pos=0,
+                name="other",
+                type=DataFrameType(columns=[]),
+                required=True,
+            ),
+        ],
+        returns=DataFrameType(columns=new_columns),
+    )
+
+    return (
+        typer._get_call_result(
+            location=location,
+            callee=signature,
+            positional=positional,
+            keywords=keywords,
+        )
+        or UnknownType()
+    )