Add crypto price converter: ETH to USD with live API support

conversions/crypto_price.py

@@ -0,0 +1,79 @@
+"""
+Convert ETH (Ethereum) to USD using live or static conversion rates.
+
+Fetches current ETH price from CoinGecko API or uses fallback rate.
+Source: https://api.coingecko.com/api/v3/simple/price
+"""
+
+
+def eth_to_usd(eth_amount: float, eth_price_usd: float = 2000.0) -> float:
+    """
+    Convert ETH amount to USD equivalent.
+
+    Args:
+        eth_amount: Amount of ETH to convert
+        eth_price_usd: Price of 1 ETH in USD (default: 2000.0)
+
+    Returns:
+        USD equivalent of the ETH amount
+
+    Raises:
+        ValueError: If eth_amount or eth_price_usd is negative
+
+    >>> eth_to_usd(1.0, 2000.0)
+    2000.0
+    >>> eth_to_usd(0.5, 3000.0)
+    1500.0
+    >>> eth_to_usd(0, 2000.0)
+    0.0
+    >>> eth_to_usd(-1, 2000.0)
+    Traceback (most recent call last):
+        ...
+    ValueError: ETH amount cannot be negative
+    >>> eth_to_usd(1, -100)
+    Traceback (most recent call last):
+        ...
+    ValueError: ETH price cannot be negative
+    """
+    if eth_amount < 0:
+        raise ValueError("ETH amount cannot be negative")
+    if eth_price_usd < 0:
+        raise ValueError("ETH price cannot be negative")
+
+    return eth_amount * eth_price_usd
+
+
+def get_live_eth_price() -> float:
+    """
+    Fetch current ETH price from CoinGecko API.
+
+    Returns:
+        Current ETH price in USD, or 2000.0 if request fails
+
+    >>> price = get_live_eth_price()
+    >>> isinstance(price, float)
+    True
+    """
+    try:
+        import requests
+
+        response = requests.get(
+            "https://api.coingecko.com/api/v3/simple/price",
+            params={"ids": "ethereum", "vs_currencies": "usd"},
+            timeout=10,
+        )
+        response.raise_for_status()
+        return response.json()["ethereum"]["usd"]
+    except (ImportError, requests.RequestException, KeyError):
+        return 2000.0
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()
+
+    # Interactive example
+    live_price = get_live_eth_price()
+    result = eth_to_usd(1.0, live_price)
+    print(f"1 ETH = ${result:,.2f} USD (${live_price:,.2f}/ETH)")

requirements.txt

@@ -9,6 +9,7 @@ numpy
 opencv-python
 pandas
 pillow
+requests
 rich
 scikit-learn
 sphinx-pyproject