initial structure implemented

docs -> _docs

helpers/robust_kernels.py

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+import numpy as np
+
+
+class RobustKernels:
+    @staticmethod
+    def huber(residual: float, delta: float = 1.0) -> float:
+        raise NotImplementedError
+
+    @staticmethod
+    def cauchy(residual: float, c: float = 1.0) -> float:
+        raise NotImplementedError
+
+    @staticmethod
+    def tukey(residual: float, c: float = 4.685) -> float:
+        raise NotImplementedError
+
+    @staticmethod
+    def huber_weight(residual: float, delta: float = 1.0) -> float:
+        raise NotImplementedError
+
+    @staticmethod
+    def cauchy_weight(residual: float, c: float = 1.0) -> float:
+        raise NotImplementedError
+
+    @staticmethod
+    def compute_robust_covariance(
+        residuals: np.ndarray,
+        kernel: str = "huber",
+        **kwargs,
+    ) -> np.ndarray:
+        raise NotImplementedError
+